There was a question on how set field background color in FileMaker based on a color in another field:

So we define a field which gets a color using formatting rules. The other field defines the hex color code to use. To keep it smaller, we only allow 4096 colors: Those where the two digits per color channel are equal. So from 000000 to FFFFFF with steps of 11. e.g. put FF0000 here to make field background red.

To generate the conditional formatting rules, we use a Xojo app:
The workflow is like this:

Cut or copy a field in layout mode in FileMaker.

Go in the app and type the right field name for the condition.

Press the button to add formatting rules.

Paste field in layout with colors.

Please try it. To change/build the Xojo app, please download Xojo on the Xojo website. For just running the project with your custom modifications in the IDE, you won't need to buy a license.